A therapeutic product delivery device is described which comprises a device body 21 and a cartridge 26 for holding a therapeutic product. An engagement structure 410, 420 is provided for releasably engaging the cartridge 26 with the device body 21. A fault detector is provided for detecting a fault in the delivery of the therapeutic product from the cartridge. A release trigger 430, 440 is responsive to the detection of a fault to cause the engagement structure 410, 420 to release the cartridge 26 from the device body 21. In this way, a fault causes the cartridge to be ejected from the device body 21, which will prevent any further delivery of the therapeutic product to the patient. The cartridge 26 may also be manually detached using release actuator 460. The therapeutic device may be an insulin pump device.
